Despite decades of research characterizing the structure and function of numerous cell types in the retina, the encoding properties of retinal amacrine cells remain largely unknown. The overall goal of my research is to contribute to our current understanding of visual processing in the retina by characterizing the intrinsic properties and connectivity of two newly identified retinal amacrine cell subtypes. To determine the physiological properties and synaptic microcircuitry of the CRH-1 retinal amacrine cell. I will be the first to (A) characterize the light responses of genetically labeled CRH-1 amacrine cells to a variety of visual stimuli. I will then (B) place CRH-1 into the context of a functional circuit by identifying postsynaptic retinal ganglion cells. These measurements will allow me determine whether CRH-1 cells could mediate feedforward inhibition in the inner retina. To examine the dynamics of gap-junctional coupling between nNOS-2 amacrine cells and the role of this network in visual processing. In preliminary experiments characterizing another genetically labeled amacrine cell, nNOS-2, I have discovered that these cells form an extensive coupled network. I will examine (A) whether nNOS-2 coupling is modulated by mean luminance and whether the modulatory signaling pathway involves dopamine or nitric oxide. I will also (B) determine how nNOS-2 coupling impacts visual response properties by measuring dendritic morphology and receptive fields in the same cells.